Mercury and other vapor electric lamp.



H. A. KENT & H. G. LAGELL. MERCURY AND OTHER VAPOR ELECTRIC LAMP.

APPLICATION FILED DBO. 1,1908.

Patented Nov. 9, 1909.

w l/E/VTORS flan A drew Km UNITED STATES PATENT orrion.

HENRY ANDREW KENT, OF BOUNDS GREEN, AND HAROLD GEORGE LACELL, OF FINCH- LEY, ENGLAND, ASSIGNORS T0 SILICA SYNDICATE LIMITED, OF LONDON, ENGLAND.

MERCURY AND OTHER VAPOR ELECTRIC LAMP.

I Specification of Letters Patent.

Patented Nov. 9, 1909.

Application filed December 1, 1908. Serial No. 465,483.

To all whom it may concern:

Be it known that we, HENRY ANDREW Knu'r, a subject. of the King of Great Britain and Ireland, of The Poplars, Maidstone Road, Bounds Green, in the county of Middlesex, England, engineer, and HAROLD (inoucu LACELL, a subject of the King of Great Britain and Ireland, of Ardoch,

i side) to prevent the condensation of the mercury at the negtaive electrode. This Nether street, Finchley, in the said county of Middlesex, chemist, have invented new and useful Improvements in Mercury and other Vapor Electric Lamps, of which the following is a specification.

This invention relates to electric lamps in which a vaporizable conductive material,

such, for instance, as mercury, is vaporized and an arc formed through such vapor.

Although this invention is especially de- 1 signed for application to lamps such as are described in the specification of our application for Letters Patent- No. 456,066 A. D. 1908, it may be applied to other lamps on .theaforesaid principle and more particularly to that form of mercury vapor lamp in which the temperature of the vapor of mercury in the arc space approximates what is known as a red heat.

For brevity we will refer to the vaporizable matter used as being mercury, and in describing the invention We will refer to the accompanying drawing, wherein- Figure 1 is an elevation of a lamp according to this invention, Figs. 2 and 3 are vertical section and plan views respectively of a modified construction, and Figs. 4 and 5 vertical and horizontal sections of another modification.

In such lamps as hitherto made difficulty has arisen owing to mercury vapor being carried over from the positive, and hotter, electrode, and deposited on the negative, and cooler, electrode, so that, eventually, the whole of the mercury may be distilled from the hotter positive electrode and condensed on the cooler negative electrode, and the lamp become inoperative. We have found that this difficulty is overcome by heating the lamp sufliciently at, or near, the negative electrode to revent such condensation. This may be one (as shown in Fig. 1 as applied to a lamp made in accordance with our, aforesaid application for patent) by winding on the tube 1 of the lamp a heating wire 2 wholly, or principally, at, or near,

-. the negative electrode end 3 of the lamp.

may be done for example as follows :The tube 1 of the lamp is made so that the portion where the positive electrode is situated is brought in contact with, or close to, the part at which the negative electrode is situated. Owing to the proximity of these two portions, the heat generated in the positive electrode (or in such electrode and are vapor on the one side) is conveyed, by conduction and radiation, to the negative electrode, so that it is heated to a higher temperature than that to which it would be heated by conduction from the are only. In consequence of this heating of the negative electrode, the two electrodes automatically adjust themselves in such a way that (other conditions being the same) the temperature of the two electrodes is the same, and consequently, when once the arc is started through the mercury vapor, there will be no greater tendency for mercury to be lost from the one electrode than from the other.

As the temperature of the arc is higher than that of the electrodes, the temperature of a portion of the negative electrode may be made to exceed that of the positive electrode by heat imparted to it from a part of the are at the positive end of the arc tube lying alongside a part of the tube containing the negative electrode.

Figs. 2 and 3 show a lamp with the part of the tube in which the arc is formed bentup and the respective electrode portions at and 5 and parts at 6 of the tubes in close proximity to each other.

Instead of bending the tube to bring the positive and negative ends into proximity, the lamp may be made, as shown in Figs. 4 and 5, of a tube 1 divided by an internal longitudinal partition 7, extending to near the end of the tube 1 farthest from the electrode portions 4: and 5, the said electrode portions being one on each side of the said partition 7, and the said partition 7 making the said tube 1 into what'is tpractically the equivalent" of a tube bent ack' upon itself.

Other ways of accomplishing the same or a substantially similar result will readily suggest themselves and we do not limit ourselves to the arrangements shown and described.

When the lamp is started, the' current through the coil 8, which has been.used for heating and vaporizing the mercury to start the arc, can be cut off, by a short c-irculting device such for instance as by bringing a-' part of, or branch from the tube, as is not directly heated by the are when the lamp has been started and is in normal operation. Such a branch from the lamp to receive the coil 8 is shown at 9.

We claim as our invention:

1. In a vapor electric lamp of the type described, means in close proximity to the electrode heated for raising the temperature of said electrode to substantially that of its companion of difierent polarity whereby the condensation of vapor at the electrode heated.

4 is. prevented.

2. In a vappr electric lamp of the type described, means in close proximity thereto for heating the negative electrode to substantially the temperature'of the. positive electrode whereby the condensation of vapor at the negative electrode is prevented.

3. In a vapor electric lamp of the type described, means in close proximity thereto for heating the negative electrode to substantiallythe temperature of the positive electrode by heat radiated during the operation of the lamp, substantially as and for the purpose described.

4. In a .vapor electric lamp of the type described, means for automatically heating the negative electrode to substantially the temperature of the .positive electrode by the heat of a closely juxtaposed portion of the lamp at a higher temperature, substantially as and for the purpose described.

5. In a vapor electric lamp of the-type described, a negative electrode and a posltive electrode closely juxtaposed to maintam the temperature of said electrodes subscribed;

'6. In a vapor electric lamp of the type described, a'negative electrodetogether with a positive electrode and'arc chamber closely juxtaposed to said negative electrode .to

maintain \the temperature of said electrodes substantially equal, as and for the purpose described. I

.In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

HENRY ANDREW KENT. HAROLD GEORGE LACELL. Witnesses:

THOS. BRINTON, 7 WILLIAM GERALD REYNOLDS.

stantially equal, as and for thepurpose de- 

